Vibratory packing machine



Oct. 1, 1957 W. S. BOHLMAN ETAL VIBRATORY PACKING MACHINE Filed April 1.1953 3 Sheets-Sheet 1 9 IGIiSS /l5 I o 0 .FIG.3

WALTER S. BOHLMAN JACK 4D. HAYES,

M PM

AG E'NT I Oct. 1, 1957 Filed April 1. 1953 W. S. BOHLMAN ETAL VIBRATORYPACKING MACHINE s I 68 1 63 Ill" i 59 '8"! 50 FIG. 6

3 Sheets-Sheet 2 WALTER S. BOHLMAN JACK D. HAYES,Jn

INVENTORS AGENT Oct. 1, 1957 w. s. BOHLMAN ET AL 2,807,975

VIBRATORY PACKING MACHINE Filed'April l, 1953 5 Sheets-Sheet 3siiif\\\\\\\\\m FIG. ll FIG. I2

WALTER S.BOHLMAN JACK 0. HAYES,J|

INVENTORS BY W WM AGENT FIG. I

2,867,975 Eatented Oct. 1, 1957 VIBRATORY rAcKINo MACHINE Walter S.Bohlman and Jack D. Hayes, Jr., Wilmington,

DeL, assignors to Hercules Powder tlompany, Wilrnington, DeL, acorporation of Delaware Application April 1, 1953, Serial No. 345,115

13 Claims. (Cl. $6-2tl) This invention relates to a vibratory packingmachine and more particularly to a vibratory packing machine especiallyadapted to the packing of large size explosive cartridges. 7

Packing by vibration is, in most cases, a very desirable and easy methodof packaging loose, pulverulent materials. As long as it is onlynecessary to fill the container or to settle a predetermined weight of aparticular material in a container, it has been found that vibration canusually be employed quite readily. Problems, of course, arise in thedetermination of the particular type of vibrator or the particularfrequency of vibration which will give optimum performance and powereconomy with a given material. For example, it has been found with knownvibratory packing equipment that a high-speed vibration does not lenditself to the packing of light, fluffy, materials such as soap chips oraluminum leafing powder. With heavier materials it has been found thatwith known equipment, high vibration frequency and greater force of eachoscillation are necessary. The solution of these problems has been foundin the designing of specific electric or fluid-actuated vibrators forparticular applications at considerable expense. As a result, the actualuse of vibratory packing has been relatively limited despite its overallattractiveness.

A problem of even greater magnitude has been encountered in attemptingto pack an entire container to a uniform density. In the packing of mostmaterials, a substantially uniform density is not important as long as acertain weight of the material is packed in a prescribed space. In suchapplications as the packing of explosive cartridges, however, it is veryoften essential that the entire cartridge be packed as near as possibleto a uniform density. Further, it is equally important and desirable topack successive cartridges to substantially the same density in order toobtain the same brisance and detonation velocity in successivecartridges of the same type. In the past, various types of vibratorypacking machines employing various sources of vibration have been triedbut to the present time no successful vibratory packer for explosivecartridges has ever been developed.

The first attempts to pack explosive cartridges by vibration weredirected to the use of eccentric wheels and cam mechanisms whichimparted a jolting motion to the shuttle holding the cartridge. It wasalso attempted to employ fluid-operated jolters similar to those used infounding machines in packing sand around molds. Both of these types werecompletely unsuccessful. The speed of vibration of each was relativelyslow with the result that the bottom portion of the cartridge was ofgreatest density with a progressive diminution in density toward thetop. Furthermore, neither type of device was satisfactory in packingexplosives from the safety standpoint.

There are now available many types of high speed vibrators, but none ofthese have proved successful in explosive packers. Electric vibratorscannot be safely used because of the undesirability of having anelectrical device in close proximity with explosive materials. Currently available fluid-actuated vibrators are characterized by vibrationfrequencies which are either too high or too low and are furtherunsatisfactory in that they do not combine a satisfactory power deliverywith a satisfactory frequency. While their frequency can be varied byvarying the pressure of the actuating medium, the changed speed ofvibration is accompanied by a corresponding change in the power of thevibration.

As a result, the manufacturers of explosives are universally packinglarge size explosive cartridges by hand and are employing the well knownHall-type or Kimbertype packing machine for smaller cartridges. Packingwith the Hall-type or Kimber-type machine is achieved by forcingexplosive into the shells by means of reciprocable tamping rods. Whileleaving much to be desired in speed and uniformity of packing, thesepackers do an acceptable job with the smaller explosive cartridge.Consequently, most of the improvements in explosive packers havecentered around this type of machine. However, the Hall-type machine hasnot been found feasible for cartridges of above two inches in diameter.A few Kimbertype machines have been rebuilt to pack cartridges up tofive inches in diameter but have not been used to any great extent.

Now in accordance with the present invention, large size explosivecartridges may be quickly packed to a high and uniform density byvibration. Furthermore, in accordance with an additional embodiment ofthe vibratory packing machine of the invention, the power of thevibration and the vibration frequency may be independently andpositively controlled to achieve the optimum packing efficiency for anygiven material at the lowest possible power expenditure.

Generally described, the present invention comprises a platen havingrigidly attached thereto a pneumatic vibrator having a unidirectionalpower stroke upwardly and substantially parallel to the vertical axis ofthe platen, support means for the platen, and resilient mountings connecting the platen to its support means. According to variousembodiments of the invention, the unit of a platen vibrator, resilientmountings and platen support means is, by suitable supporting members,mounted in combination with means for introducing the materials to bepacked into the containers and means for raising and lowering the platenassembly with relationship thereto. According to an additionalembodiment of the invention, means are provided for rigidly positioningthe cartridges on the platen during the packing operation. According tostill further embodiments of the invention, various pneumatic vibratorshaving a unidirectional power stroke are employed in conjunction withthe platen and/or the means for introducing the material into thecontainers.

In order to be operable as the shuttle vibrator in the vibratory packerof the invention, the vibrator must have a unidirectional power stroke.Preferably, the vibrators used in the invention will also be equippedwith frequency control valves which will enable the operator to employ avibration of the necessary force and frequency to give optimum packingefiiciency. The preferred vibrator has in combination a casing forming acylinder, a reciprocable piston disposed in the cylinder, exhaust portslocated in the casing adjacent the opposite ends of the cylinder, an airinlet for pressurized air leading to one end of the cylinder, an airexit passage for air compressed by the piston leading from the oppositeend of the cylinder, and a valve assemblyysaid valve assembly having incombination a first passageway therethrough which is in communication atone end with the air inlet in the vibrator casing and at the other endwith a source of pressurized air; a second passageway therethrough, oneend of which is in communication with the air exit passage in thevibrator casing and the other end of which leads to the atmosphere, saidsecond passageway having a check valve at the end thereof whichregisters with the air exit passage and a metering means for air at theend thereof leading tothe atmosphere; and slidable means disposed withinthe valve assembly which is movable in one direction to close the firstpassageway under the force exerted by the compressed air admitted to thesecond passageway through the check valve and which is movable in theopposite direction to open the first passageway under the force exertedby the pressurized air when suflicient of the compressed air is releasedto the atmosphere through the metering means. v I

If a vibrator is employed which does not have a fre quency control valveassembly, the vibrator preferred has in combination a casing forming acylinder, a reciprocable piston mounted in the cylinder, an annulusformed in the cylinder wall substantially equidistant from the endsthereof, a passage extending longitudinally into the piston at a pointwhich registersiwith the annulus in the cylinder Wall when the piston isin the down position and which remains in communication with saidannulus during a substantial portion of the pistons upward :powerstroke, a duct leading from said passage and opening into the cylinderfrom the bottom of the piston, and exhaust ports located in the casingadjacent the opposite ends of the cylinder, the distance between theexhaust ports being substantially equal to the length of the piston;

Also included in the present invention is a process or system forpacking pulverulent materials to a high and uniform density whichcomprises introducing the pulverulent material into a container,intermittently imparting a plurality of vertical upwardly appliedimpulses to the container and allowing the container to fall freelyafter each upwardly applied impulse. In one specific embodiment of thisprocess,.the upward movement of the container continues until theinertia supplied by the upward impulse is dissipated. Then the containeris allowed to fall freely until the next upward impulse is applied. Thistype of motion is obtained with the apparatus of the invention when thecontainers are not secured to the platen. In a further embodiment ofthis process, the upward motion of the container is gradually arrestedand the free fall of the container is gradually decelerated prior toapplication of the next upward impulse. This type of motion is obtainedwith the apparatus of the invention when the containers are secured tothe platen. In either type of vibratory movement, there is no forceother than gravity applied during the downward travel of the containerwith the result that packing accomplished by the upward force applied isnot undone by a reversely applied force.

Having generally described the present invention, further and morespecific illustration is given with reference to the accompanyingdrawings wherein reference symbols refer to like parts wherever theyoccur. In the drawings, Fig. 1 is an elevational plan view of avibratory packingm'achine in accordance with an embodiment of theinvention. Fig. '2 is a side, part elevational, part sectional view ofthe deviceof Fig. 1. Fig. 3 is a plan view of the device of Figs. 1 and2 taken along line 3-3 of Fig. 2. Fig. 4 is a part elevational, partsectional view of the device of Figs. 1, '2, and 3 taken along line 4-4of Fig. l or Fig.2. Fig. 5 is a. plan view of an embodiment of thepreferred platen vibrator. Fig. 6 is a part elevationalfpart sectionalview of the vibrator of Fig. 5. Fig. 7 is apart elevational, "partsectional view of an alternate portion of a' vibrator valve assemblywhich may be substitutedfor the corresponding portion of the valveassembly of thevibr'ator shown in Fig. 6. Fig. 8 is an elevational endview of the vibrator of Fig. 6. Fig. 9 is'a part elevational, partsectional view of a vibrator which maybe used for either the feed hopperor platen vibrator. Fig. 10 is a part elevational, part sectional viewof an alternate hopper vibrator. Fig. 11 is a sectional view of one ofthe resilient hopper mountings shown in Figs. 2 and 4. Fig. 12 is asectional view of one of the resilient platent mountings shown in Figs.2 and 4. Fig. 13 is a sectional view of a feed hopper nipple shown inFig. 4. Fig. 14 is a part sectional, part elevational view of theshuttle box positioning means shown in Fig. 4.

Referring now to the drawings, and more particularly to Figs. l-4, avibratory packing machine is shown in which a steel base plate 10 issecured by bolts 11 to a 'hardwood base 12 over a pit 13 lined withconcrete 14. Secured to the base plate 10 on cast brass bases 15 arethree stanchions 16 formed from heavy brass pipe. Cast brass caps 17with vertically extending projections 18 are secured to the upper endsof the stanchions 16. Secured to the vertical projections 18 of thestanchion caps 17 is an aluminum hopper supporting frame 19. Attached tothe hopper supporting frame 19 by brass cap screws 20 are hoppermounting plates 21 containing stepped bores 22. Fitted into the bores 22are bronze casings 306 shown in detail in Fig. 11. A feed hopper 24 isconnected to the feed hopper supporting frame 19 by studs 25 andtube-form resilient mountings 26, which support- 7 ing assembly will bespecifically described with reference @to Fig. 11.

Disposed in the bottom of the feed hopper 24 is a bronze nipple plate 27having nipples 28 extending downward therefrom. Each of the nipples 28has a constriction 29 formed immediately adjacent to its egress orificeas shown specifically in Fig. 13. A pneumatic vibrator 30 is secured tothe hopper support frame 19 at an angle of about 20 below thehorizontal. The vibrator 30 has a unidirectional power stroke in thedirection away from the hopper 24 and will be subsequently described indetail;

Disposed below the hopper assembly and over the base plate 10 is arectangular aluminum platen 31 having rigidly attached thereto andsuspended therefrom a pneumatic, vibrator 32, various embodiments ofwhich will be specifically described hereinafter with reference to Figs.59. The platen is secured to aplaten support frame 33 by means ofresilient mountings 34 which will be subsequently described withreference to Fig. 12. Disposed in one side of the platen 31 arerubber-capped positioning studs 35. Secured to the opposite side of theplaten 31 is a fluid-actuated gripping piston assembly 36 which will besubsequently described with reference to Fig. 14. Disposed on the platen31 between the positioning studs 35 and gripping piston assembly 36 is ashuttle box 37. The shuttle box 37 may loosely hold the container to beloaded so as to allow free vertical movement or may hold the containersrigidly and thus transmit the movement of the platen 31 directly "to thecontainers. 'An air delivery pipe 38, which is connected to a power line(not shown) by a rubber hose 39, supplies air to both the vibrator 32and also to the gripping piston assembly '3 6 by means of a passage 40in the platen as shown in Fig. 14.

A cylinder 41, maintained in position by guy rods 42, is disposed belowthe platen assembly and extends downward into the pit13. Within thecylinder 41 is mounted an elongated piston 43 which is actuated by afluid mediumadmitted to the bottom of the cylinder through an inlet'44.The upper endof t .e piston 43 is connected to the platen support frame33 by means of bolts 45. The distance to which the platen 31 can beraised by the piston 43 is determined by the setting of the lock nuts 46on guide rods 47. The guide rods 47 passthrou'gh bushings 48disposed inoiifices'i'n the base plate it and are-connected to the platen supportframe '33 midway between the resilient mountings 34. A bellows 49 issecured toh the top of 'baseplate '10 and the bottom'of the plate 31"and preventsthe material being packed'or foreign matter from gainingaccess to the area enclosed therein.

In Figs. 5, 6, and 8 is shown an embodiment of the preferred pneumaticvibrator having a unidirectional power stroke for use on the platen asshown in Fig. 4. In this preferred pneumatic vibrator a reciprocablepiston 50 is positioned in cylinder 51 formed by a casing 52. An airinlet 53 to the cylinder is located in one end of the casing 52 andexhaust ports 54 and 55 are positioned in the casing 52 at pointsequidistant from the ends of the cylinder. The distance between exhaustsports 54 and 55 is such that during reciprocation one end of the pistonbegins to cover one port as the other end of the piston begins touncover the other port. An additional air exit passage 56 from thecylinder 51 is situated in the casing 52 at the end opposite the airinlet port 53. A threaded plug 57 seals the bottom of the vibratorcasing 52 and is of a size which enables insertion and withdrawal of thepiston 50.

Aftixed to the side of the vibrator casing 52 by bolts 58 and sealinggasket 59 is a valve assembly having a casing 60 which forms a chamber61 having two portions of difierent diameter. A recess 62 is located inthe valve casing 60 and is in communication with the air exit passage 56in the vibrator casing 52. A thread 63 is formed in valve casing 60 andextends into the chamber 61. A recess 64 is formed in the wall of casing66 opposite the thread 63. A threaded spring-actuated check plug 65threadedly engages the thread 63 with the base of the plug -eingretained in the recess 64. Check plug 65 has ports 66 and 67 locatedrespectively in the upper and lower walls thereof. A valve 68 in checkplug 65 allows the passage of compressed air through ports 66 and 67into the chamber 61 from the recess 62 but prohibits a reverse flow.Above the check plug 65 the casing 60 is threaded to receive a threaded,adjustable exhaust valve 69. The valve 69 is adjusted by screw 70 andwhenever the valve 69 is partially or fully open, chamber 61 is incommunication with the atmosphere through the ports 66 and 67 in thecheck plug 65 and through the valve 6?.

An air inlet 71 is located in the valve casing 60 near the closed end ofthe portion of chamber 61 having the smaller diameter. A passage 72,formed by a recess in the valve casing 69, is in communication withinlet port 53 in the vibrator casing 52. In communication with recess7?. is a passage 73 which opens into chamber 61 above the air inlet 71.Recess 74 in the casing 26 is a continuation of passage 73 acrosschamber 61 and into the casing 69. Also in communication with the recess72 is a passage 75 which opens into the chamber 61 at a point abovepassage 73. Passage 76 is a continuation of passage 75 across chamber 61and through casing 66 to the atmosphere.

A reciprocable piston 77 is disposed in slidable, substantiallyair-tight relationship in the portion of the valve chamber 61 having thesmaller diameter. An annular groove 78 is cut in the piston 77 at apoint which causes the groove 78 to register with passages 75 and 76when, as shown, the piston is fully Within the portion of the chamberhaving the smaller diameter. The distance to which the piston 77 mayextend into this portion of the chamber is governed by the projection 79of the threaded plug 80 disposed in the threaded opening 81 of the valvecasing 60 at the base of the chamber 61.

A piston 82 is disposed in slidable, substantially airtight relationshipbelow check plug 65 in the portion of the chamber having the greaterdiameter. The length of the piston 82 is such that when it is forcedupward by the piston 77, the lower end of the piston 77 is able to clearthe upper edge of passage 73 and recess 74, thus bringing air inlet 71and passage 72 into communication. An annulus 83 is formed in the wallof chamber 61 at the point where the piston 82 meets the piston 77 whenthe piston 77 is resting on the projection 79 of the plug 86. An orifice84 is provided in the valve casing 60 which leads from the annulus 83 tothe atmosphere, thus allowing air to enter the large portion of thechamber 61 under the piston 32 when said piston is forced upward by thepiston 77. When the piston 82 returns to the position shown in Pig. 6,the air admitted on the upstroke exhausts to the atmosphere.

Threaded sockets 85 are provided in the top of the vibrator casing 52for securing the vibrator to the platen. Sockets 86 are provided in theplug 57 to receive a spanner for securing the plug 57 in place.

Referring particularly to Fig. 7, a portion of a valve assembly is shownwhich may be substituted for the corresponding portion of the valveassembly shown in Fig. 6. A chamber 61 is formed in a casing 60 and isclosed at its lower portion by a threaded plug having a projection 79'.An air inlet 71' is disposed in the casing 60 and opens into the chamber61' at a point substantially opposite the projection 79' of the threadedplug 86'. A recess 72 is formed in the casing 60'. A passage 73 leadsfrom the recess 72' and opens into the chamber 61' at a point above theair inlet 71. The passage 73' is extended across the chamber 61' andextends a short distance into the opposite cylinder wall to form arecess 74'. A reciprocable cylindrical piston 37 is disposed inslidable, substantially air-tight relationship within the chamber 61'.It is at once apparent that the structure shown in Fig. 7 dii'fers fromthe corresponding portion of the valve assembly shown in Fig. 6 only inthat the exhaust passages 75 and 76 and annular groove 78 in the piston77 of Fig. 6 have been omitted. The substitution of the portion of thevalve assembly of Fig. 7 for the corresponding portion of the valveassembly of Fig. 6 results only in a slightly shorter power stroke ofpiston 50 since less air is able to escape from the cylinder 51 duringthe exhaust stroke of the piston 50. The structure shown in Fig. 6 ispreferred although the increased air cushion below the piston inherentin the structure of Fig. 7 gives quieter operation.

The vibrator illustrated in Figs. 5, 6, and 8 operates as follows:Pressurized air is admitted through air inlet 71 of the valve assembly.Pistons 77 and 82 are forced upward by the pressure of the incoming airand the pressurized air flows through passage 73, passage 72, and airinlet 53 to cylinder 51 at the base of the vibrator piston 50. Vibratorpiston 50 is forced upward and once the piston has closed exhaust port54, the remaining air in the top of the cylinder 51 is compressed andforced through air exit passage 56, recess 62 and the check plug 65 intothe chamber 61 above the piston 82. Due to the fact that the area of theend of the piston 82 is greater than the area of the end of piston 77,the air compressed in the valve assembly above piston 82 is able toforce pistons 82 and 77 downward, whereupon the lower end of the piston77 shuts oif the flow of incoming air through air inlet 71. Dependingupon the setting of the needle valve 69, a certain period of time isrequired for sufiicient of the pressure above the piston 82 to be bledto the atmosphere. Once sufficient of the pressure above the piston 82has been released, the pressure of the incoming air through air inlet 71is able to force the piston 77 upward once more and allow thepressurized air to flow to the vibrator cylinder 51 at the base of thevibrator piston 50. While the piston 82 is depressed, however, thevibrator piston 50 falls due to the force of gravity and the expansionof the air cushion at the top of the cylinder 51. When the vibratorpiston 56 falls, the air below the piston is exhausted through exhaustport 55 and backward through air inlet 53 to passage 72 from which it isbled to the atmosphere through passage 75, the annular groove 78 in thepiston 77, and passage 76. Once the exhaust port has been covered by thefalling vibrator piston 50, the passage provided through the valveassembly is the only 1 note;

7 means of exhaust from thelower part of the vibrator cylinder 51;

It is at once apparent that the frequency of the vibrator described canbe altered at will merely by adjusting needle valve 69 to vary the rateat which the air is released to the atmosphere from above piston 82.This variation in vibration frequency is achieved without any diminutionwhatsoever in the force of the individual power stroke of the vibratorpiston 50. Consequently, it is possible to vary both the force of theindividual power stroke and the vibration frequency to suit the demandsof the particular material being packed with the vibratory packingmachine of this invention.

In Fig. 9 is shown a part sectional, part elevational view of apneumatic vibrator having a unidirectional power stroke which may beeasily converted for use as a platen vibrator or as the hopper vibrato-rin the vibratory packing machine in accordance with the invention. Areciprocable piston 90 is disposed in a cylindrer 89 formed by a casing91. The lower portion of the'casing 91 is formed by a cylinder head 92which is held in air-tight relationship to the remander of the casing 91by a gasket 93 andstuds 94-. An annulus 95 is formed in the wall. ofthecylinder at a point equidistant from the ends thereof. Passages 96and 97 are formed in the outer periphery of piston 90 at points whichregister. with the center of annulus 95 when the piston 90 isalternately at the end of either its exhaust or power stroke. A duct 98leads from the passage 96 through the piston 90, to the bottom of piston90. A duct 99 leads from the passage 97 through the piston 90 to the topof the piston 90. Duct 98 is plugged with a threaded plug 100. Exhaustports 101 and102 are disposed in the wall of the cylinder at a pointequidistant from the ends of the cylinder. The distance between theexhaust ports 101 and 102 is such that during reciprocation one end ofthe piston begins to cover one exhaust port just as the opposite end ofthe piston begins to uncover the other exhaust port. A threaded airinlet port 103 is disposed in one sideof the casing 91, and leads intothe annulus 95. .A, threaded ,air inlet port-104 is disposed in theopposite side of the casing 91 andalso leads into the annulus 95. Athreaded plug 105 is disposed in the air inlet port 104. A steppedaperture 106 is formed in the cylinder head 92 and disposed therein is alength of pipe 107 having a flange which registers with the shoulder 108of the aperture 106. A

reciprocable piston 109 is mounted in the bore'of the pipe 107 inslidable, substantially air-tight relationship. The lower portion of thebore of the pipe .107 is threaded to receive an air hose 110 from acompressed air line or a sealing plug (notshown). The bore of the pipe107 is constricted and forms a shoulder 111 which limits the downwardmovement of the piston 109 to its own length.

Passages 112 and 114, sealed by threaded plugs 113 and 115,respectively, are provided for the attachment of the vibration frequencycontrol valve assembly similar to that shown in Fig. 6. To adapt thecontrol valve assembly shown in Fig. 6 to the vibrator of Fig. 9, it isonly necessary to extend the recess 72 upwardly in the direction ofrecess 62 for a distance sufficient to bring recess 72 intocommunication with air inlet 103 when recess 62 is in communication witheither of passages 112- and 114, respectively. Suitable threaded holesmust beformed in casing 91 to accommodate bolts 58. When fitted with thecontrol valve assembly, the frequency of the vibrator of Fig. 9 may bepositively controlled while maintaining a stroke of uniform power.

As shown the vibrator of Fig. 9 is adapted for use as the hoppervibrator and operates as follows: Compressed air is admitted throughhose 110-to the bore of the pipe 107 below the piston 109 at a pressurenecessary to raise the; piston 1 0 9 and thus force the piston 90upward. The isin pi to 9 au e o. xhau t. hrou h the exhaust port 102.Once the piston 90.has closed the exhaust .port 102; the air in the endof the cylinder is compressed to form a cushion which prevents pistonfrom striking the top of the cylinder. When the piston 90 has beenraised to the up position, compressed air is admitted through air inlet103 which flows through the annulus 95, passage 97, and the duct 99 tothe cylinder above the piston 90. The piston 90 is forced downward tothe bottom of the cylinder. As the passage 97 in the piston 90 passesthe lower edge of the annulus 95, the

air to the top of the cylinder 89 is shut oif and as the upper edge ofthe piston 90 uncovers the exhaust port 102, the air above the pistonbegins to exhaust to the atmosphere. Meanwhile as the piston 90 isforced downward, the air below the piston is exhausted through exhau'stport 101, and the piston 109 is forced downward into the pipe 107 bythebase of the piston 90. The piston 109 in the bore of pipe 107 isprevented from entering pipe 107 beyond its own length by the shoulder111. A cushion of air is also formed on the lower part of the pistonwhich prevents the piston from striking the cylinder head 92. Due to thecushions of air formed at the ends of the cylinder during the exhauststroke and the power stroke of the piston 90, the vibrator illustratedis characterized by a relative quietness in operation.

To adapt the vibrator as shown in Fig. 9 for use as the shuttle vibratorin the vibratory packing machine of the invention, the air hose 110 isdetached from the pipe 107 and replaced by a suitable sealing plug. Theplug 105 -is removed from the air inlet 104 and is placed in air inlet103. The hose from the air line is then con-' nected to air inlet 104.The plug 'is removed from the duct 98 and placed in the duct 99. Whencompressed air is now admitted through air inlet 104, the operation ofthe vibrator is identical to that shown in Fig. 9 except that the powerstroke of the piston 90 isup instead of down. Since the piston will fallby gravity when the flow of pressurized air to the base of the piston isshut oif, no means for returning the piston to its original position isnecessary. Consequently, when the vibrator is used as the shuttlevibrator, the pipe 107 may be removed from cylinder head 92 and replacedby a suitable plug.

In Fig. 10 is shown an alternate embodiment of a vibrator which may beused as the hopper vibrator in the vibratory packing machine of theinvention. A cylinder 200 is formed by a casing 201 and a cylinder head202 threadedly engaged in one end thereof. A reciprocable piston 203 ismounted in the cylinder 200. Exhaust ports 204 and 205 are located inthe cylinder wall equidistant from the ends of the cylinder and areseparated by a distance such that one end of the piston 203 begins touncover one of the exhaust ports as its opposite end begins to cover theother. An air inlet port 206 in the casing opens into one end of thecylinder while an air exit passage 207' leads from the opposite end ofthe cylinder. A stepped orifice 208 is formed in the cylinder head 202,and disposed therein is a flanged pipe 209 having acentrally disposedstepped bore 210. The lower end of the pipe 209 is threaded to receivean air hose 211 leading to an air line (not shown). A reciprocablepiston 212 is mounted in'the bore 210 of the pipe 209. The travel of thepiston 212 into the bore 210 of'the pipe is limited to its own length bythe shoulder 213 formed by the constriction of the stepped bore 210.

Aifixed to the side of the vibrator casing 201 by a gasket 220 and studs221 is a valve assembly having a casing 223 which forms a chamber 224having sections of difierent diameters. A recess 225 is located in thevalve casing 223 and is in, communication with the'air exit passage 207in the vibrator casing 201. A thread 226 isv formed in the valve casing223 and extends into the chamber 224. A recess 227 is formed in the wallof he. c s n rqpos he hr adJZG- A h e d d spring-actuated check plug 228threadedly engages the thread 226 with the base of the plug beingretained in the recess 227. The check plug 228 has ports 229 and 230located respectively in the upper and lower walls thereof. A valve 231in the check plug 228 allows the passage of compressed air through ports229 and 230 into the chamber 224 from the recess 225 but prohibits areverse flow. The casing 201 is threaded at its lower end to receive athreaded adjustable exhaust valve 232. The valve 232 is adjusted byscrew 233 and whenever the valve 232 is partially or fully opened, thechamber 224 is in communication with the atmosphere through ports 229and 230 in the check plug 228 and through the valve 232.

An air inlet 234 is located in the valve casing 223 near the closed endor" the portion of the chamber 224 having the smaller diameter. Apassage 235 is formed by a recess in the valve casing 223. Incommunication with the recess 235 is a passage 236 which opens into thechamber 224 below the air inlet 234. Recess 237 in the casing 201 is acontinuation of passage 236. Also in communication with the recess 235is passage 238 which opens into the chamber 224 at a point below thepassage 236. Passage 239 is a continuation of passage 238 across thechamber 224 and through casing 223 to the atmosphere.

A reciprocable piston 240 is disposed in slidable, substantiallyair-tight relationship in the portion of the valve chamber 224 havingthe smaller diameter. An annular groove 241 is cut in the piston 240 ata point which causes the groove to register with the passages 238 and230 when the piston 240 is fully within the portion of the chamberhaving the smaller diameter. The distance to which the piston 240 mayextend upwardly into this portion of the chamber is governed by theprojection 242 of the threaded plug 243 disposed in the valve casing 223in the top of the chamber 224.

A piston 250 is disposed above the check plug 228 in slidable,substantially air-tight relationship in the portion of the chamber 224having the greater diameter. The length of the piston 250 is such thatwhen it is forced downward by the piston 240, the upper end of thepiston 240 is able to clear the lower edges of the passage 236 andrecess 237, thus bringing air inlet 234 and passage 235 intocommunication. An annulus 251 is formed in the wall of the cylinder 224at the point where the piston 250 meets the piston 240 when both are atthe limit of their upward movement and when the piston 240 is in contactwith the projection 242. A passage 252 is provided in the valve casing223 which leads from the annulus 251 to the atmosphere, thus allowingair to enter the large portion of the chamber 224 above the piston 250when said piston is forced downward by the piston 240. When the piston250 is again forced to the up position, the air admitted on the downstroke exhausts to the atmosphere. 1

Threaded sockets 260 are provided in the top of the vibrator casing 201for securing the vibrator to the hopper. Sockets 261 are provided in thecylinder head 202 to receive a spanner for securing the cylinder head inplace.

It will be seen that the operation of the vibrator shown in Fig. issimilar to that of the vibrator shown in Figs. 5-8, the only differencesbeing that the valve assembly has been invertedto give a power stroke inthe down direction, and means have been provided at the bottom of thecylinder for returning the vibrator piston to the up position inpreparation for each power stroke. As in the case of the vibrator shownin Figs. 5-8, the vibration frequency may be positively controlled byadjusting the needle valve 232 and thus regulating the period necessaryfor the air line pressure to overcome the pressure below the piston 250.

In Fig. 11 is shown one of the resilient mounting assemblies employed toconnect the feed hopper 24 to 5 tremity thereof.

70 during the packing operation.

10 the inner tube 304 and is disposed equidistant from the ends of theinner concentrically disposed tube 304. A stepped bore 22 is formed inthe hopper mounting plate 21 and is lined with a bronze casing 306machined to fit the stepped bore 22 in the hopper mounting plate Theinner diameter of the casing is also stepped to ,form an annularshoulder 307. The lower end of the outer tube 303 of tube-form resilientmounting 26 is disposed upon the shoulder 307. The portion of theelongated stud extending above the stop nut 300 is disposed in a recessformed in the body of the hopper 24. Four similar mountings are disposedas shown in Fig. 1.

In Fig. 12 is shown in detail one of the resilient mounting assembliesemployed to connect the platen 31 to the platen support frame 33. Thisparticular assembly comprises two plate-form resilient mountings 34mounted in a series on a brass cap screw 310 and separated by a brasswasher 311. Each of the plate-form mountings shown consists of a steelsleeve 312 having bonded about its periphery in shear a mass of rubber313. An annular plate 314 is disposed in the outer edge of the mass ofrubber 313 and protrudes therefrom. The plate 314 is secured in theannular orifice of a cup-shaped support member 315 by a crimp 316. Thecup-shaped support member has an annular flange 317. The annular flange317 of the upper mountings is secured to the underside of the platen 31while the annular flange of the lower mounting is secured to the uppersurface of the platen support frame 33. A recess 318 is provided in theunderside of the platen 31 and a recess 319 is provided in the upperside of the platen support frame 33 to allow the ends of the brass cupscrew 310 to reciprocate without touching the platen or the platensupport frame.

In Fig. 13 a feed nipple 28 is shown which comprises a bronze tubehaving an annular projection 330 and an annular flange 331 near theupper end thereof to secure the nipple in the nipple plate 27. Anannular constriction 29 is formed around the inner periphery of theegress orifice of the nipple 28. The size of the individual nipple andthe number of nipples employed depend upon the size and number of theexplosive cartridges or other containers being filled. Once thecontainers become filled, the material being introduced can no longerpass into the containers and cores are formed in the feed nipples.

When the vibration of the hopper and shuttle is stopped and the nipplesare disengaged from the mouths of the containers, the constriction 29causes the nipples to retain the cores. When the nipples are thenlowered into empty containers, the cores are removed when vibration isresumed. While it is preferred to form a constriction in a cylindricalbore as shown, similar results can be obtained by employing a nipplewith a tapered bore. Coring can only be uniformly obtained with Straightbores when the material being packed is characterized by extremely poorflowing qualities.

Referring particularly to Fig. 14, a sectional view of a portion of theplaten assembly is shown to illustrate the operation of the shuttle boxgripping piston assembly 36 which holds the shuttle box in position onthe platen The gripping piston assembly 36 shown in Figs. 3 and 4 has acasing formed by a base member 33, a cylinder head 334 and a pistonguide member 335. The base member 333 and the cylinder head 334 aremaintained in tight sealing rela tionship by means of gaskets 336 and337 and studs 338.

11 The piston guide member 335 is held in forced fit by the flange 339of the base member 333. The casing so formed defines a cylinder 340. e Apiston 341 having an enlarged head 342 is concentrically maintained inthe cylinder 340 by the piston guide member 335. The enlarged pistonhead'342 is grooved to receive a packing ring 343. The small oppositeend of the piston 341 ex tends from the guide member 335. A rubber cap344 is secured to the end ofthe piston 341 extending beyond the pistonguide member 335 by a pin 345.

One end of a bellows 49 is secured to the piston guide member 335 andthe other end of the bellows 49 is secured to the rubber cap 344. Thepiston 341 has. a bore 346 extending from the end protruding from thepiston guide member 335 to'the enlarged piston head 342. Th bore 346 isin communication with the inside of the bellows 49 through a passage347. The bore 346 is also in communication with the cylinder 340 througha passage 348. The enlarged piston head 342 of the piston 341 isnormally held in the position shown by the coil spring 349. Air from thepower line is delivered to the cylinder 340 on the opposite side of theenlarged piston head 342 through a passage 40 which passes through theplaten 31, the base member 333 and the cylinder head 334.

When air is supplied through passage 40 to the end of the cylinder 340,pressure is exerted on the enlarged piston head 342 causingthe piston341 to move through the piston guide member 335 until the rubber cap 344engages the shuttle box 37 and secures it in position against thepositioning studs 35 on the opposite side of the platen 31. The spring349 is compressed by the movement of the piston and when the airpressure on the piston head 342 is removed, the piston 341 is returnedto the position'shown' by the action of the spring 349, and the shuttlebox 37 is released,

The packing of large size explosive cartridges on the vibratory packingmachine of the invention will now be described with reference to thedrawings and particu larly to Fig. 4. A shuttle box 37 containing thedesired number of explosive cartridges of the desired size is placedupon the platen 31 and positioned securely against the stop studs 35. Anipple plate 27 containing the desired number of nipples of the sizedesired to correspond with the number and size of cartridges of theshuttle box 37 is attached to the feed hopper. Fluid medium is thenadmitted to cylinder 41 at the base of the piston 43 and the platen israised on its support by the piston duced into the right side of thehopper as shown in Fig. 4

and is conveyed to the left as a result of the vibratory movement of thehopper being downward and to the right. The explosive material thereforeflows through the nipples and into the shells below. The particular typeof vibration induced in the platen 31 by the pneumatic vibrator 32causes the explosive to be packed in the shells to a high and uniformdensity. When the shells are filled to the desired density and degree,and a core has formed in the nipples, the supply of air to the hoppervibrator 30, the platen vibrator 32 and the gripping piston assembly 36is shut off. The pressure of the fluid medium beneath the piston 44 incylinder 42 is released, and the platen 31 is allowed to settle to itsdown position. Due to the annular constriction 29 .at their egressorifice, the cores are maintained within the nipples. The shuttle box offilled shells 38 is removed for crimping and scaling, is replaced by abox of empty shells and the operation is. repeated. When vibration ofthehopper is resumed, the cores are dislodged'into the empty containers. Ifdesired. the cartndges can. be

' construction could be substituted for those employed in.

loosely filled with. explosive prior to initiating vibration in the'platen, As previously indicated, the shells themselves may be looselycontained in the shuttle box or may be rigidly secured in the box sothat the movement of the box is transmitted directly to the shells.

While it is not intended that the following theory of operation of thevibratory packing machine in accordance with this invention should inany way restrict the actual scope of the'invention, it is believed itssuccess in packing explosive materials to their necessarily high anduniform density is due to a number of cooperating features. Theunidirectional power stroke of the platen vibrator in an upwarddirection forces the material to be packed into the bottom of thecontainer. If the upward power stroke were followed by a downward powerstroke which acted on the shell, the container would be driven away fromthe packed material and much of the work done by the upward stroke'wouldbe undone. However, in accordance with the invention, Whether thecontainers are loosely or rigidly held in the shuttle box, no downwardforce is applied and only packing force is ever applied to thecontainer. When the containers are rigidly secured in the shuttle box,the free fall ofv the piston, cushioned at the bottom of its fall by anair cushion in the bottom of.

the cylinder together with the cushioning provided by theresilientimountings, allows successive packing strokes without anyappreciable intermediate loosening. The resiliencyof the platenmountings also causes a relatively gradual deceleration of the upwardmovement of the platen, of the shuttle box, of the cartridge, and of theexplosive and consequently, does not undo any substantial portion. ofthe packing accomplished by the upward thrust'of eachzpower stroke.Furthermore, since the fall of the vibrator piston is cushioned by theair beneath the piston and since the fall of the platen following thepower stroke is also cushioned by the resiliency of the mountings, nosubstantial jarring takes place which would tend toloosen the materialin the cartridge. When the preferred controllable speed vibrator isemployed as the platen vibrator, the optimum vibration frequency can beobtained for each material to be packed.

In order toobtain an explosive cartridge having a high and uniformdensity, it has further been found that a pneumatic vibrator having aunidirectional power stroke packing machine which'are within the scopeof the in-.

vention will become apparent to those skilled in the art of vibratorypacking and to those skilled in the art of manufacturing pneumaticvibrators. The specific design and overall structure of all the parts ofthe particular machine described and illustrated are obviously notessential to its success. For example, means for elevating the platenother than the fluid-actuated cylinder disclosed could be substitutedwhich might prove equally desirable. The support stanchions and supportframes could obviously be arranged in a manner different from thatspecifically illustrated, and any suitable materials of weighed levers.Coil springs have generally been found to be unsatisfactory since arelatively more rapid change in strength takes place which brings abouta substantial change in the movement of the platen over a period of Ifthe vibrator is. not so attached, satisfactory time. Furthermore, coilsprings are most undesirable in the packing of explosives from thesafety standpoint, since coil springs are known to snap. The breaking ofa coil spring is often accompanied by sparks which might possibly causean explosion despite the fact that the platen, its support frame and theresilient mounting are preferably surrounded by a protective bellows asshown in the drawings. The specific type of mounting illustrated isgreatly preferred since it is very easy to install or to replace, givesexceptionally long wear, and has been found to impart the most effectivemotion to the platen.

It is preferred that the exhaust ports of the vibrators of the inventionbe spaced evenly from the ends of the vibrator cylinders and that theseports be separated by a distance substantially equal to the length ofthe piston. With this arrangement the best results are achieved bothfrom the standpoint of smoothness of operation and economy of air.However, this preferential arrangement is not essential to the operationof the vibrator. As long as the port being uncovered by the pistonduring the power stroke is located far enough from the end of thecylinder to enable the piston to gain sufiicient velocity, the momentumof the piston will insure completion of the stroke even though the portis open during the last portion of the stroke. When the piston isreturned to its starting point, either by gravity or other means, theport should be located close enough to the end of the cylinder to allowmost of the air to exhaust and thus give a substantially full stroke.The auxiliary exhaust means shown in the drawings is helpful in thisregard.

The exhaust port being covered by the piston during the power strokeshould be placed close enough to the opposite end of the cylinder toallow the piston to make a substantially full stroke but should belocated far enough from the end of the cylinder that enough air istrapped and compressed in the end of the cylinder to fully depress thevalve piston or other slidable means in the valve assembly. All of thesefactors must be coordinated to give optimum results in each particulardesign and size of vibrator in accordance with the invention.

It is preferred that two separate but coacting pistons be employed inthe valve assembly as illustrated in the drawings. A single pistonhaving two different diameters is operable, but is not preferred becausethe single piston is more difficult to lap to the substantiallyair-tightfit necessary to satisfactory operation of the valve assembly.

In view of the fact that many modifications of the invention arepossible, it is to be understood that the invention is to be limitedonly by the scope of the appended claims.

This application is a continuation-in-part of my copending applicationSerial No. 134,530, filed December 22, 1949, now abandoned.

What we claim and desire to protect by Letters Patent is:

1. In a vibratory packer especially adapted to the packing of large sizeexplosive cartridges, the combination which comprises a platen havingrigidly attached thereto and vertically suspended therefrom a pneumaticvibrator having a unidirectional power stroke upwardly and substantiallyparallel to the vertical axis of the platen, support means for theplaten and resilient mountings conmeeting the platen to its supportmeans, said pneumatic vibrator having in combination a casing forming acylinder, a reciprocable piston disposed in the cylinder, exhaust portslocated in the casing adjacent the opposite ends of the cylinder, an airinlet for pressurized air leading to one end of the cylinder, an airexit passage for air compressed by the piston leading from the oppositeend of the cylinder, and a valve assembly; said valve assembly having incombination a first passageway therethrough which is in communication atone end with the air inlet in the vibrator casing and at the other endwith a source of pressurized air; a second passageway therethrough,

one end of which is in communication with the air exit passage in thevibrator casing and the other end of which leads to the atmosphere, saidsecond passageway having a check valve at the end thereof whichregisters with the air exit passage and a metering means for air at theend thereof leading to the atmosphere; and slidable means disposedwithin the valve assembly which is movable in one direction to close thefirst passageway under the force exerted by the compressed air admittedto the second passageway through the check valve and which is movable inthe opposite direction to open the first passageway under the forceexerted by the pressurized air when sufficient of the compressed air isreleased to the atmosphere through the metering means.

2. In a vibratory packer especially adapted to the packing of large sizeexplosive cartridges, the combination which comprises a frame, a hopperequipped with feeding means for introducing explosive material into thecontainer, said hopper being connected to the frame by resilientmountings, means for vibrating the hopper, a platen disposed below thehopper having rigidly attached thereto and vertically suspendedtherefrom a pneumatic vibrator having a unidirectional power strokeupwardly and substantially parallel to the vertical axis of the platen,support means for the platen, and resilient mountings connecting theplaten to its support means; said pneumatic vibrator having incombination a casing forming a cylinder, a reciprocable piston disposedin the cylinder, exhaust ports located in the casing adjacent theopposite ends of the cylinder, an air inlet for pressurized air leadingto one end of the cylinder, an air exit passage for air compressed bythe piston leading from the opposite end of the cylinder, and a valveassembly; said valve assembly having in combination a first passagewaytherethrough which is in communication at one end with the air inlet inthe vibrator casing and at the other end with a source of pressurizedair; a second passageway therethrough, one end of which is incommunication with the air exit passage in the vibrator casing and theother end of which leads to the atmosphere, said second passagewayhaving a check valve at the end thereof which registers with the airexit passage and a metering means for air at the end thereof leading tothe atmosphere; and slidable means disposed within the valve assemblywhich is movable in one direction to close the first passageway underthe force exerted by the compressed air admitted to the secondpassageway through the check valve and which is movable in the oppositedirection to open the first passageway under the force exerted by thepressurized air when sufficient of the compressed air is released to theatmosphere through the metering means.

3. In a vibratory packer especially adapted to the packing of large sizeexplosive cartridges, the combination which comprises a frame, a hopperequipped with feeding means for introducing explosive material into thecontainer, said hopper being connected to the frame by resilientmountings, means for vibrating the hopper which consists of a pneumaticvibrator having a unidirectional power stroke, said vibrator beingmounted on the hopper at an angle which causes one component of forcefrom the power stroke to be directed along the horizontal axis of thehopper opposite the desired direction of flow of the material to bepacked and another component of force to be directed downward along thevertical axis of the hopper, said vibrator being equipped with means toreturn the vibrator piston to its original position against gravityprior to each power stroke, a platen disposed below the hopper havingrigidly attached thereto and vertically suspended therefrom a pneumaticvibrator having a unidirectional power stroke upwardly and substantiallyparallel to the vertical axis of the platen, support means for theplaten, and resilient mountings connecting the platen to its supportmeans; at least one of said hopper vibrator and said platen vibratorhaving in ombination a "casing forming a cylinder, a reciprocablepistondisposed in the cylinder, exhaust ports located in the casingadjacent the opposite ends of the cylinder, an air inlet for pressurizedair leading to one end of the cylinder, an air exit passage for aircompressed by the piston leading from the opposite end of the cylinder,and a valve assembly; said valve assembly having in combination a firstpassageway therethrough which is in communication at one end with theair inlet in the vibrator casing and at the other end' with a source'ofpressurized air; a second passageway therethrough, one end of which isin communication with the air exit passage in the vibrator casing andthe other end of which leads to the atmosphere, said second passagewayhaving a check valve at the end thereof which registers with the air'exit passage and a metering means for air at the end thereof leading tothe atmosphere; and slidable means di-sposedwithin the valve assemblywhich is movable in one direction to close the first pa s sageway underthe force. exerted by the compressed air admitted to the secondpassageway through the check valve and which is movable in the oppositedirection to open the first passageway under the'force exerted by thepressurized air whenv sutficient of the compressed air is released tothe atmosphere through the metering means.

4. In a vibratory packer for packing explosive cartridges, thecombination which comprises a platen; means including a movable massconnected to said platen for applying an upward impact to the platen andmeans for applying power ot said mass in one direction only; supportmeans for said platen and resilient mountings connecting said platen toits support means; a hopper above said platen for supporting apulverulent explosive material for delivery to a cartridge; and saidplaten being adapted to support an elongated cartridge to receive flowof explosive material from said hopper.

5. A packer in accordance with claim 4 wherein said means for applyingsaid impact to said platen and for applying said power to said mass is apneumatic vibrator assembly rigidly attached to said platen and adaptedto apply said impact in a direction substantially parallel to thevertical axis of said platen.

6. A packer in accordance with claim '5 wherein said hopper is adaptedto deliver explosive material to a plurality of cartridges and containsa separate nipple extending from its bottom side for engaging each saidcartridge to deliver said explosive material thereto; each said nipplehaving a lesser diameter at its egress orifice than at its ingressorifice. I

7. A packer in accordance with claim 5, including at least one cartridgedisposed on said platen; a pulverulent explosive material in saidhopper; and each said cartridge being adapted to receive flow ofexplosive material from a bottom side of said hopper.

8. A packer in accordance with claim 5 wherein said pneumatic vibratoris substantially vertically suspended from said platen.

9. A packer in accordance with claim 5 wherein said pneumatic vibratorcomprises in combination a casing forming a cylinder, 2. reciprocablepiston mounted in the cylinder, an annulus formed in the cylinder Wallsubstantially equidistant from the ends thereof, a passage extendinglongitudinally into the piston at a point which registers with theannulus in the cylinder wall when the piston is in the down position andremains in communication with said annulus during a substantial portionof the pistons upward power stroke, a duct leading from said passageandiopening into the cylinder from the bottom of the piston, and exhaustports located in the. casing adjacent the opposite ends of the cylinder,the distance between the exhaust ports being substantially equal to thelength of the piston.

10. A packer in accordance with claim 5 wherein said pneumatic vibratorcomprises in combination a casing forming a cylinder, a reciprocablepiston mounted in the a cylinder, an annulus formed in the cylinder wallsubstantially equidistant from the ends thereof, a passage extendinglongitudinally into the piston at a point which registers with theannulus in the cylinder wall when the piston is in the down position andremains in communication with said annulus during a substantial portionof the pistons upward power stroke, a duct leading from said passage andopening into the cylinder from the bottom of the piston, and exhaustports located in the casing adjacent the o'pp'ositc ends of thecylinder, the distance between the exhaust ports being substantiallyequal to the length of thepisto'n. 7

11. A packer in accordance with claim 5 including a frame; said hopperbeing connected to the frame by resil-. ient mountings; and means forvibrating said hopper.

12. A packer in accordance with claim 11 wherein said pneumatic vibratorcomprises in combination a casing forming a cylinder, '21 reciprocablepiston mounted in the cylinder, an annulus formed in the cylinder wallsubstantially equidistant from the ends thereof, a passage extendinglongitudinally into the'piston at a point which registers withfth'eannulus in the cylinder wall when the piston is in the down position andwhich remains in communication with said annulus during a substantialportion ofthe pistons upward power stroke, a duct leading fromsaidpassageandopening into the cylinder from the bottom of thc piston,and exhaust ports located in the casing adjacent the opposite ends ofthe cylinder, the distance between the exhaust ports being substantiallyequal to the length of the piston.

13. A packer in accordance with claim 11 wherein said means forvibrating the hopper comprises a pneumatic vibrator mountedon' thehopper at an angle which causes one component of force from the powerstroke to be directed along the horizontal axis of the hopper oppositethe desireddirection of. flow of the material to be packed and anothercomponent of force to be directed downward along the vertical axis ofthe hopper, said vibrator being equipped with means to return thevibrator piston to its original position against gravity prior to eachpower stroke, and a platen disposed below the hopper.

References Cited in the file of this patent UNITED STATES PATENTS218,658 Bolton et a1 Aug. 19, 1879 1,434,583 Bates Nov. 7, 19222,150,913 Drew L. Mar. 21, 1939 2,298,252 Davis OCT. 5, 1942 2,379,230G'rlflin June 2 6, .1945 2,404,434. Clark .et a1. July 23, 1946 FOREIGNPATENTS 808,489 France Nov. 14, 1936

